Lubricants



Patented Nov. 28, 1944 LUBRICANTS Eugene Lieber, West New Brighton, Staten Island,

Y., and Aloysius F. Cashman, Bayonne, N. J., assignors to Standard Oil Development g.

Company, a corporation of Delaware No Drawing. Application January 1, 1942, Serial No. 425,351

8 Claims.

a sufliciently high film strength for lubricating moving metal parts which contact each other under high pressures, such as certain types of bearings, engines, gears, etc. It is also known that the film strength or load-carrying capacity of such mineral oils can be greatly increased by adding thereto various chemical compounds or materials containing active halogen and/or sulfur, and sometimes phosphorus, but these various materials, although very efiective in carrying the high loads demanded of extreme pressure lubricants, have a serious disadvantage that during storage, especially in contact with certain metals such as iron, they undergo some type of degradation or change which tends to make certain constituents thereof insoluble and precipitate out.

It has now been found that the addition of small amounts, of certain types of materials to the extreme pressure lubricating agents or to the lubricants in which they are compounded, will stabilize them against such tendencies to form an insoluble precipitate or sediment. With this primary object in view, another object of the invention is to accomplish this desired stabilization without interfering -or materially reducing the extreme pressure lubricating characteristics of the lubricant and without materially increasing the corrosive tendencies of such lubricants toward metals withwhich they come in contact. Broadly, the invention comprises adding to such extreme pressure agents from which an insoluble precipitate or sediment tends to settle out during storage, a small amount of a stabilizer comprising a low molecular Weight aromatic compound having not'more than two nuclei condensed together in one radical and having not more than 2/n nuclear substituents, where n equals the number of nuclei condensed in one radical.

Numerous types of aromatic compounds come within the scope of this invention; for instance, among the aromatic hydrocarbons which can be used may be included mono-nuclear aromatic compounds such as benzene, and various monoor di-alkyl substituents thereof such as toluene, xylene, amyl'benzene, para-cymene, etc., as well as compounds containing two or more separate mono nuclear groups such as di-phenyl and the like, and compounds containing two condensed nuclei such as naphthalene and various monoalkyl derivatives thereof such as amyl naphthalene, or partially hydrogenated .derivatives 'such as di-hydro naphthalene and the dimer or other lower polymers of di-hydro naphthalene. Ether and sulfur derivatives of such aromatic hydrocarbons may also be used such as diphenyl oxide, beta naphthyl ethyl ether, thiophenol, sulfanilic acid, phenothiazine, etc. Certain other types of aromatic derivatives may be used such as butyl phthalate. phenolphthalein.

Thus, it is one of the primary objects of the invention to use a cyclic compound, of the class described, as an addition agent to the extreme pressure agent per se in order to stabilize the latter against insolubilizing degradation during storage. Another feature of the invention is the use of such stabilizing compounds in blends of a mineral or hydrocarbon lubricating oil bas stock containing an extreme pressure agent normally soluble therein and therefore already dissolved therein,

The amount of the stabilizer to be used according to this invention should normally be within the approximate limits of about 1% to 15%, preferably about 2% to 10%, about 5% having been found very suitable, based on the weight of extreme pressure agent, or about 0.1-3%, preferably about 0.2-2.0% based on the total lubricant.

The extreme pressure lubricant to which the above-describedstabilizers may be added according to this invention, may be prepared by incorporating into a mineral oil base stock derived from any of the commonly used crude petroleum oils 8. compound containing active halogen and a compound containing active sulfur, or one or more compounds containing both halogen and sulfur in the same molecules. The invention is particularly applicable to extreme pressure lubricants containing corrosive chlorine compounds, for instance, chlorinated aliphatic or aromatic hydrocarbons such as chlorinated derivatives of paraflln wax, kerosene, aromatic petroleum fractions, or coal tar solvents. The amount of ,chlorine to be used will of course depend upon crease the suitability of the lubricant for use under high temperatures, and the sulfur compounds to be used may be, for instance, sulfurized fatty or mineral oils such as sulfurized sperm oil, or aliphatic sulfur compounds such as organic sulfides, mercaptans, dior poly-sulfides, xan thates, xanthogen sulfide, thiocarbonates, etc. These compounds may be used in such amounts that about 1% to 30% of sulfur is incorporated in the active or combined state, on the basis of the extreme pressure lubricating agent per se, or about 0.5% to 10% based on the total lubricant.

Instead of using separate chlorine compounds and sulfur compounds; it is possible to use single materials in which both sulfur and halogen have been incorporated. For instance, a suitable raw material such as paraifin wax or a liquid petroleum distillate such as kerosene, may be treated with a sulfur halide such as sulfur monoor dichloride, in order to incorporate both sulfur and chlorine. A different method and one which is generally preferred commercially because it permits better technical control is to chlorinate a suitable raw material such as paraflin wax, kerosene, or naphtha, to the desired chlorine content, and then subsequently treat the resultant compound with sulfur or an inorganic sulfide such as sodium sulfide or polysulfide, or a mixture thereof with sulfur and sodium hydroxide, or an organic sulfur compound such as thiocarbonate or xanthate.

One example of a suitable extreme pressure lubricatin agent is one made by chlorinating kerosene to a chlorine content of about 25% to 50%, such as35%,- by passing chlorine through kerosene at atemperature of about 175 to 200 R, and adding to the resultant chlorinated kerosene an isopropyl alcohol solution of aqueous caustic soda and sodium hydrogen sulfide containing free sulfur admixed therewith, using a reflux temperature for a reaction time ranging between about /2 hour and 5 or hours. The resultant product may, for instance, contain 70% sulfur and 33% chlorine, or, as another example, might contain 65% sulfur and 31% chlorine. Ordinarily, the stabilizers of this invention will 'be needed more, and therefore be of greatest advantage when extreme pressure lubricating agents are used which contain a large amount of sulfur and chlorine.

A compound made by this method and having this latter composition, and marketed under the trade name Parapoid, Will be referred to as Extreme pressure agent A, in the tests reported herebelow.

Another example of an extreme pressure lubricating agent which may be used is one made by similarly chlorinating kerosene to a chlorine content of about 25% to 50%, preferably about 30% to 40%, and treating the resultant chlorinated kerosene with sodium xanthate, as, for instance, in alcohol solution. The sodium chloride forms and separates out, and the liquid product is distilled free of alcohol, leaving a product, for example, which may contain 9% sulfur and 32% chlorine. Acompound marketed under the trade ple of Extreme pressure (E. P.) agent, the preparation of which has been described hereinabove.

Each of the resulting blends was split into two parts, one part being placed in a glass container, and the other into a similar container having therein a strip of boiler plate unpolished sheet mild steel (the same as used in tanks) (1" x 2" x These containers were then placed in an oven thermostatically controlled at 150 F. for 24 hours. As a control test, the original Extreme pressure agent A was placed in similar containers, i. e. with and without a strip of steel, and was subjected to a storage temperature of 150 F. for 24 hours. 1

In order to determine the extent of quality degradation as regards solubility in mineral oil,

. the samples of E. P. agent A which had undernamefsantopoid is understood to be made by thisprocedure.

Extreme pressure lubricants made by adding to-,-a lubricating oil base stock separate chlorine and sulfur compounds may be made, for instance, by using about 10% by weight of chlorinated paraffin wax. containing 40-50% of chlorine and 10% of sulfurized sperm oil containing 10% sulfur.

The mineral oil base stock may beobtained from a parafiinic, naphthenic, or mixed base crude and when the stabilizer is added to an extreme pressure lubricant consisting of a mineral oil base stock and an extreme pressure agent one test as described above, after cooling to room temperature were blended to 10% (by weight) in a Panhandle Bright Stock to form a series of four extreme pressur lubricants. These blends were allowed to stand at room temperature for five days and observation was made on the condition of the blends.

The aromatic materials of this invention which were subjected to the above test are listed herebelow:

Naphthalene Di-hydro naphthalene Dimer of di-hydro naphthalene Para-cymene Beta-naphthyl ethyl ether Di-phenyleneoxide Sulfanilic acid Phenothiazine In the control sample of E. P. agent A, a large amount of sediment was observed both in the plain glass container and in the glass container having the iron (steel) present. In. all of the other tests in whichthe stabilizers listed above were used, little or no sediment or precipitate was present at the conclusion of the test, thus indicating that the aromatic hydrocarbons as well as the ether, sulfur and partially hydrogenated derivatives thereof coming within the scope of this invention, all were effective in stabilizing the extreme pressure agent against development and settling out of an insoluble precipitate or sludge during storage under severe test conditions.

Some of these stabilizers were dissolved in a mineral lubricating oil base stock and then subjected to similar storag tests, and they were found satisfactorily effective in stabilizing the In. bricant against insolubilizing degradation during storage.

. Although the theory as to the exact mechanism of the operation of the invention is not well understood, it is believed that the stabilizer of this invention tends to prevent a self-polymerization of the extreme pressure agent to a heavier and insoluble form during storage. The extreme pressure agent may selectively react with the stav ascasso biiizer to form a soluble but still eflective ex-'- treme pressure molecule instead of reacting with itself to form a higher molecular weight insoluble product.

In preparing extreme pressure lubricants ac-. cording to this invention, other known addition agents may be incorporated if desired, for instance, fatty oils, soaps of fatty acids or naphthenic acid, other materials having thickening,

viscosity-index improving and pour-depressing properties, anti-oxidants, oil-soluble metal soaps,

, dyes, etc.

Divisional application Serial No. 539,010, filed June 6, 1944, contains claims on disclosed species other than those claimed herewith, and also contains more generic claims on the stabilized ex-' treme pressure agent per se, .and on the method of stabilizing such extreme pressure agents;

It is not intended that this invention be limited to any of the particular examples which have been given merely for illustration, nor by any theory asto the mechanism of the operation of the invention, but only by the appended claims in which it is intended to claim all novelty inherent in the invention as well as other modifications coming within the scope and spirit of the invention. l a Z We claim: 1. An extreme pressure agent containing active halogen and sulfur in amounts suficient to im-' part load-bearing characteristics and normally tending during storage to undergo degradation leading to the formation of ingredients which are insoluble in paraiflnic mineral oils, to which has been added a small amount, sufllcient to stabilize ainst such degradation, of a compound having the following formula: 1

in which R is selected from the class consisting of hydrogen atoms and alkyl groups.

2. Product according to claim 1, in which the stabilizer is naphthalene.

3. An extreme pressure lubricating agent contaming-about 540% of chlorine and about 140% oi sulfur, and derived by chlorinating a petrolemn hydrocarbon traction and treating the resultant chlorinated hydrocarbon material with a sulfurizing agent, to which has been added a amountofanalkylated naphthalene hydrocarbon between the approximate by weight.

4. An extreme pressure lubricating agent normally tending during storage to undergo insolubilizing degradation, and containing about 25-40% by weight of chlorine and about 540% of sulfur, and is made by chlorinating kerosene limits of 1%. and 15% and treating the resultantchlorinated kerosene with a. sodium polysulflde sulfurizing agent, to

which extreme pressure agent has been added a small amount between the approximate limits of about 145% by weight of naphthalene, said amount being suiiicient to stabilize against such degradation.

5. An extreme pressure lubricant comprising a 7 major proportion of mineral lubricating oil, a minor proportion of an extreme pressure lubricating agent of the sulfur chlorine type normally soluble therein before storage but tending during storage to undergo degradation leading t th formation of an insoluble sediment or sludge. and asmallamount ofastabilizeradaptedtoprevent such degradation during storage, said stabilizer consisting essentiallyof a compound having the 3 formula: I

ALOYSIUB F. C. 

